Research finds no statistically significant evidence linking increases in transit
utilization to reductions in congestion

Thomas A. Rubin

December 30, 2013

Statistical analysis of the 74 largest urbanized areas in the U.S. over a 26-year
period suggests that increasing transit utilization does not lead to a reduction
in traffic congestion; nor does decreasing transit utilization lead to an increase
in traffic congestion.

Policies designed to promote transit utilization can in certain instances increase
traffic congestion—as appears to have been the case in Portland, Oregon.

Vehicle-miles traveled per freeway lane-mile is strongly correlated with traffic
congestion: the more people drive relative to available freeway capacity, the worse
congestion gets.

Data from New York and Los Angeles indicate that the most effective way to increase
transit utilization is by reducing fares, as well as by improving basic, pre-existing
service.